This invention relates to a method of and structure for manufacturing open top, walled members such as troughs, runners, ladles and other vessels which are used for containing and processing molten iron and steel. It is well known in the art that such open, top walled members may have sufficient structural integrity to support alone a molten metal poured therein.
Conventionally, troughs and runners for transporting molten iron and steel are constructed in situ near a tap spout of a blast furnace or other molten metal container. The mold for the trough or runner utilizes the existing walls of a trench or other existing structure as the outer (lower) walls of the mold. The inner (upper) walls of such molds have conventionally been formed of heavy steel plates spaced from the outer walls leaving only an open space between the outer and inner mold walls in which to pour the casting compound and to provide a venting area for the release of moisture during setting of the casting compound. In the past, heavy oil or grease was placed on the interior sides of the inner walls facing the outer walls to allow for more ease in the removal of the inner wall from the casting compound. However, when the inner walls were removed when the casting compound had sufficiently set, cracks and bubbles were formed resulting in a rough surface.
As mentioned in U.S. patent application Ser. No. 07/893,377, filed Jun. 4, 1992, and later abandoned in favor of filing a File-Wrapper Continuation on Nov. 15, 1993 and accorded U.S. patent application Ser. No. 08/153,266 still pending, whose entire contents are incorporated herein by reference, the prior art inner mold walls made of heavy steel plates can be replaced with a consumable inner wall made of an open mesh, galvanized steel screen. The use of the open mesh screen as the inner walls of the mold permits the drying process for the casting compound to be started as soon as the pouring process ends. It is not necessary to wait for the casting compound to set because the mesh screen is not removed during the drying process. There are adequate openings in the mesh screen to permit venting of moisture from the drying compound and, in fact, the mesh screen is not removed until it is melted by the molten metal being introduced into the finished trough or runner. Also, since the mesh screen is lightweight and the casting compound is of a consistency that it can be pumped into the mold cavity, cranes and hoppers are not needed in the construction of the troughs and runners, thereby reducing the cost of such an installation.
In some instances it is desired to use the mesh screen a multiple number of times for the formation of other troughs or runners. This provides a savings in cost by preserving the screen material. Manufacturing time is reduced by forming a multiple number of identical troughs or runners from a single mesh screen instead of creating a mesh screen for each trough or runner. This also provides a consistency in the quality of each trough or runner. In addition, it is sometimes desired to prevent the cold iron or steel of the screen from being dissolved into the molten metal when poured into the trough or runner since it results in a decrease in the temperature of the molten metal which decreases flow characteristics of the molten metal.
To use the mesh screen multiple times and to avoid dissolving the screen, it is necessary to remove the screen prior to the curing process to avoid the melting of the screen once the molten metal is poured into the trough or runner. As with the prior art steel plated inner walls, one would use heavy oil or grease to remove the screen from the casting compound thus causing cracking and bubbles and a rough surface.
Accordingly, it is an object of the present invention to provide a method and structure for forming a walled member having smoother surfaces with increased resistance to erosion.
It is another object of the present invention to provide a method of repairing walled members to provide a smooth surface with increased resistance to erosion.
It is another object of the present invention to provide a mold for forming a walled member which is easier to remove from the castable compound before the drying and curing process is begun.
It is another object of the present invention to provide a consumable mold having a structure to allow for forming a smoother surface and providing improved drying and curing of the castable compound.